Many modern radio frequency (RF) receivers use a direct conversion or zero-IF (ZIF) architecture. RF signals received at an antenna are fed through mixer driven by a local oscillator (LO) and subsequently filtered to produce a baseband channel demodulated output signal. Ideally, RF power amplifiers of the RF receiver would act linearly, faithfully reproducing an amplified RF signal at their output with no distortion.
As for the design targets for the RF receiver, low noise figure (NF), high third-order intercept point (IIP3) and high central frequency (fc) are required.
The mixer-first receiver has advantages, for example, good linearity, high tunable Q and low NF. The requirement on improving the IIP3 of the receiver is one of the issues.
Further, to reject out-band signals, higher order BPF (band pass filter) may be used. But, numerous off-chip BPF would increase the device cost.
Thus, there needs a wireless communication receiver architecture which achieves high linearity and requires simple external low cost LPF (low pass filter) or BPF.